Substation sender-circuit.



A. E. LUNDELL.

SUBSTATION SENDERVCIRCUH', APPLICATION FILED ma. 21. 1915.

www@ 191m Lwmm UNITED STATES PTENT FFICE.

ALBEN E. LUNDELL, or NEW YORK, N. Y., AssIGNoR To -WESTERN ELECTRIC COMPANY, or NEW YORK, N. Y., A CORPORATION oF ILLINors.

SUBSTATION SENDER-CIRCUIT.

Specification of Letters Patent.

Patented Aug. s, 1915.

Application filed February 27, 1915. A Serial No. 112052.

tems.

Heretofore in automatic telephone systems, in which the calling subscriber operates a calling device or 'impulse sending' mechanism to control. the operation of selecting apparatus, the making and breaking oi' the line control circuit b v the sending' mechanisni caused irritating noises to be set up in the calling subscribers receiver, which noises were disagreeable and sometimes dangerous.

The objectof the present invention is the provision of a substation circuit for use with a calling' device or impulse sending ,mechanism and in which all possibility of noise in the receiveridue to the makingand breakingof the control circuitby the sending mechanism is avoided.

.The invent-ion lwill be particularly described in its embodiment in the substation circuit illustrated in the accompanying drawing.

Referring to the drawing, 10` designates the usual ringer in series with a condenser 11v in the normal circuit of the line conductors 1.and 2. The telephone transmitter the induction coil 13, switch-hook 15, trans- 12 and the primary winding of an induction y coil 13 are included in a. normally open bridge of the line conductors, and are arranged to be brought into circuit upon the removal of the telephone receiver 14 from its switch-hook 15, said receiver. and the secondary winding of the induction coil 18 being` also brought into circuit upon the removal of the receiver. l

Associated with the substation .circuit is a calling device or impulse sending' mechanism 16 having a wheel 17 rotatable about the axis 18, and provided with teeth 19. A bell crank lever Q0 pivoted at 21 is located in operative relation to the Wheel 17 one arm of which isengaged by the teeth on the Wheel-17, the other arm engaging a Contact arm Q'xwhich engages with a contact 23 located 1n the line conductor ductors ill and are brought out from the induction coil leads, as shown, and terminate in the contact 2G and switch contactf27 respectively. An arm 2S is fastened to the shaft 1S and movable`with the wheel 17. This contact 26, and switch contact Q7 constitute an off-normal switch, and the closing ot' this switch, when the calling' device moves from normal, places a shunt aroundthe receiver 1-1, which shunt is maintained until after the required number of impulses is sent, and the calling 'device returns to normal.

The operation is as follows: Upon the removalof the `receiver 14 `from the switchhook ,15, the 'signaling' circuit is closed from battery thro-ugh the right windingl of the signal relay 29, line conductr 1, primary of mitter 1Q, impulse .contacts 22, :23, line conductor :2, left winding of relay 29, back to batt-ery. The subscriber' now operates the calling' device 16 by means of a dial, to send the impulses necessary to make connection with the subscriber wanted. As a preliminary to sending1V the impulses, the wheel 17, together with the arm 28, is moved in the direction'of. the arrow the required distance, after which it is returned to normal b v the action of a spring, (not shown). Upon leaving the normal position the arm 28 allows the off-normal switch to close, placing a shunt circuit 2l, 26, 27, .25 about the receiver 11. As at this time there is steady current from battery iowinfz through the primary of the induction coil, the placing' of the shunt about the receiver causes no change in the flow of current through the primary, and hence no disagreeable click is produced in the receiver. In its return .to normal the teeth 19 contacting with the bell crank 20 make and break the .signaling circuit at the contacts 23, Q3, energizing and denergizing the relay Q9 the required number of times. .The making and breaking of the signaling,r circuit produces .current changes in the primary of the' induction 'coil' 13, which produce current .changes-in the secondary. The receiver, howeser, beingr shunted, is notI affected by Athe current changes in the secondary, after the ksending, of the impulses and upon the return of the wheel 17 to normal Hrm ntf-normal switch Two con-l contacts 26, 27' are opened, but asI yat this time there is a steady flow of current from battery through the signaling circuit, there is no eii'ect produced in the receiver.

What is claimed is:

l. A substation circuit for automatic telephone systems having in combination a calling device, a signaling circuit including the primary of an induction coil, a receiver in Aseries withv the secondary of saidinduction coil, aswitchhook and mea-ns controlled v,ntlierebyffoifcompleting said signaling circuit, and a shunt about said receiver, and pontacts in said shunt operated When the vc ta'lling device leaves its normal position, whereby the shul circuit is completed.

' 2. In asubstation circuit for automatic 'telephonefsystems the combination of a line whereby a. change of potential lin the receiver lis prevented during the sending out of impulses. v

3. In a substation circuit for automatic telephone systems, the combination of a line circuit comprising tvvo branches, a receiver, an induction coil, means for placingthe primary of said induction coil in series with the line branches and the receiver in inductelephone systems, the combination of a line circuit comprising twobranches, aninduction coil, a receiverconnected 1n serieswith the secondary ',-Winding 'of said induction coil, means for'connectin'g the primary of said inductiony coil1n series With said line branches, la calling device having means for sending impulses over lsaid line branches in series, andv further meansfor placing a shunt about said ;receiver When the calling v device is vmoved from normal.

In witness whereof, 'I hereunto subscribe 4 my name this 24th day of February A. D.,

1915. ALBEN E. LUNDELL.

Witnesses:

E. EDLE'R,

WALTER J. -FEN'roN.

Copies of this patent may be lobtained for ve cents each, by addressing the Commissioner of Patents.

i Washington, D. C. 

